I played bzflag some years ago into a closed LAN with friends and now that I returned I discover some servers around the world.
Anyway I noticed some tanks behaviours that I didn't remember, could you help me?

1 - I noticed some tanks moving by their side when jumping without wings flag, is this possible ?
2 - Some tanks carrying the team flag have also other flags like wings or laser, etc ... again is it possible ?
3 - Can't lock the GM several times on target while other tanks can lock and kill me rapidly , is it question of training or just bad behaviours ?
4 - Where I can find a description of the abilities of each flag ?

"Trying to reason with a fool is like trying to teach a goldfish to bring you the newspaper"
"Sometimes people try to expose what's wrong with you, because they can't handle what's right about you."
"Measure your words -- they determine the distance of your relationships"

I'm not sure if I'm able to answer all your questions, but I'll see what I can do.

kiodos wrote:
1 - I noticed some tanks moving by their side when jumping without wings flag, is this possible ?

I've seen it done with "Agility", "Thief" and "High Speed" flags.(Usually by jumping and with a slight turn it sometimes makes it seem like they might have jumped sideways.)

2 - Some tanks carrying the team flag have also other flags like wings or laser, etc ... again is it possible ?

I'm assuming you mean a player is holding the team flag and has other powers.
This is possible with plug-ins and has been done quite a bit. (See links I've placed below.)
Also there's custom flag plug-ins and there may be flags which aren't listed which appear.

3 - Can't lock the GM several times on target while other tanks can lock and kill me rapidly , is it question of training or just bad behaviours ?

GM works by locking on the nearest tank and by locking on to it by right mouse click. (If using default configurations.)
Also depending on where you play, GM has a very tight or very lose turn ratio.(Meaning in some areas it's possible to out-dodge a GM lock and while in others it's virtually impossible.)
Also GM can lock on to teammates. (So watch out for TKs.)

4 - Where I can find a description of the abilities of each flag ?

Depends a bit as there are custom flags, but there's a list of official flags which exist.
There's a few links I've provided below which might give a general idea of some of the custom ones which exist.

Those who are critical of me, I'll likely be the same of them. ~ZehraThere's always something to remember and it's been a game I love. ~ZehraThe time spent is a time which can never be regained, so it's a time to enjoy. ~ZehraThe decisions we make are the ones we look forward too and the ones we regret. ~ZehraThere's a difference between knowing my name and knowing me, one shows respect to my name and the other is to who I am. ~Zehra

kiodos wrote:1 - I noticed some tanks moving by their side when jumping without wings flag, is this possible ?

The tanks might be hitting an obstacle mid-jump, which could be taking away their rotation.

kiodos wrote:2 - Some tanks carrying the team flag have also other flags like wings or laser, etc ... again is it possible ?

It is not possible to have the team flag and also have the effects of wings. Team flag and laser is possible via a server plugin, but I'm not sure if anyone is doing that. (Plus, it wouldn't show up as a laser for the local client as shot type modifications by a plugin do not affect the original client.) The Mofo server, for instance, has a plugin that provides a genocide effect when you are (I think) carrying your own team flag.

kiodos wrote:3 - Can't lock the GM several times on target while other tanks can lock and kill me rapidly , is it question of training or just bad behaviours ?

I'll elaborate on what Zehra mentioned. The default settings (tank speed, shot speed, and the GM turn speed) are set up so that a tank moving almost perpendicular to the direction of a locked GM can avoid being shot. Some servers increase the tank speed or shot speed, which exaggerates this, making it even easier to avoid being shot by a locked GM.

kiodos wrote:4 - Where I can find a description of the abilities of each flag ?

The Help menu in the game describes all of the flags. You can also toggle flag help while playing with the 'f' key. That would show you a description of the flag you are carrying on the screen.

"In addition to knowing the secrets of the Universe, I can assure you that I am also quite potty trained." -Koenma (Yu Yu Hakusho)

There doesn't seem to be a genocide shot type.
According to this post TeamWeapons - just started.
Not sure if this is the case in more recent versions of BZFlag.

-Zehra

Those who are critical of me, I'll likely be the same of them. ~ZehraThere's always something to remember and it's been a game I love. ~ZehraThe time spent is a time which can never be regained, so it's a time to enjoy. ~ZehraThe decisions we make are the ones we look forward too and the ones we regret. ~ZehraThere's a difference between knowing my name and knowing me, one shows respect to my name and the other is to who I am. ~Zehra